AD8122 Triple Differential Receiver with 300m Adjustable Cable Equalization

The AD8122 is a triple, high speed, differential receiver and equalizer that compensates for the transmission losses of UTP and coaxial cables up to 300 meters in length. Various gain stages are summed together to best approximate the inverse frequency response of the cable. Each channel features a high impedance differential input that is ideal for interfacing directly with the cable.

The AD8122 has two control inputs for optimal cable compensation, one LPF control input, an input to select between UTP and coax cable, and an output offset adjust input. The cable compensation inputs are used to compensate for different cable lengths; the VPEAK input controls the amount of high frequency peaking and the VGAIN input adjusts the broadband flat gain, which compensates for the flat cable loss. The VFILTER input controls the cutoff frequency of output lowpass filters on each channel. Selection between UTP and coaxial cable compensation responses is determined by the binary COAX/UTPinput, which can be left floating in UTP applications. The VOFFSET pin allows the dc voltage at the output to be adjusted, which can be useful in dc-coupled systems.

For added flexibility, the gains of each channel can be set to x1 or x2 using the associated GAIN control pins.

The AD8122 is available in a 6 mm × 6 mm, 40-lead LFCSP and is rated to operate over the extended temperature range of −40°C to +85°C.

Applications

Keyboard-video-mouse (KVM)
Digital signage
RGB video over UTP cables
Professional video projection and distribution
HD video
Security video

Features and Benefits

Compensates cables to 300 meters for wideband video
60 MHz Equalized BW @ 300 meters of UTP Cable
120 MHz Equalized BW @ 150 meters of UTP Cable
Fast time domain performance
70 nsec settling time to 1% with 300 meters of UTP cable
7 ns rise/fall times with 2 V step @ 300 meters of UTP cable
3 frequency response gain adjustment pins
High frequency peaking adjustment (V_PEAK)
Output lowpass filter cutoff adjustment (V_FILTER)
Broadband flat gain adjustment (V_GAIN)

Selectable for UTP or coax compensation
DC output offset adjust (VOFFSET)
Low output offset voltage:
±4 mV @ G = 1
Compensates both RGB and YPbPr
Two on-chip comparators with hysteresis
Can be used for common-mode sync extraction
Available in 40-lead, 6 mm × 6 mm LFCSP